São Paulo Federal Institute of Education, Science and Technology

About: São Paulo Federal Institute of Education, Science and Technology is a education organization based out in São Paulo, Brazil. It is known for research contribution in the topics: Context (language use) & Computer science. The organization has 1707 authors who have published 2374 publications receiving 11333 citations.

Direct Power Control Strategy to Enhance the Dynamic Behavior of DFIG during Voltage Dip

Abstract: One issue of using doubly fed induction generator operating in parallel with the grid is the vulnerability of the power-electronic converter when voltage sags in the supply terminals of the generator occur. The sudden reductions of voltage at the supply terminals of the generator produce high current transients in the stator and rotor windings. This transient can exceed the rotor-side converter limits and, consequently, the dc-link voltage limit. In order to improve the dynamic performance of stator and rotor current in this condition, a direct power control is proposed to improve the dynamic performance of the stator active and reactive power. The direct power control strategy is based on rotor voltage equation which does not ignore the transient stator voltage and flux. The consequence of the optimum stator power control is the reduction of the current peaks during the voltage sags. Experimental results show a good performance of the proposed strategy when the DFIG is subject the balanced and unbalanced voltage sags.

Análise do processo de alfabetização científica em crianças em espaços de educação não formal e divulgação da ciência

Abstract: We understand Science Literacy as a citizens' right and a lifelong process that occurs in different educational spaces. We assume that the child, understood as an active actor, participant and producer of culture, can be considered an agent of science literacy, through the promotion of dialogue between children's cultures and scientific culture. The aim of this paper is, based on the theoretical-methodological framework of Science Literacy Indicators, to analyze the applicability of the tool for the study and evaluation of educational and science communication activities for children. The framework consists of four indicators (Scientific, Social Interface, Institutional and Interaction) and their attributes. In this sense, we present the indicators articulating with aspects of childhood and supported by results of empirical studies to exemplify and discuss their use for analysis of educational actions in non-formal education spaces. Finally, we discuss the role of this framework in the process of evaluation and planning of educational actions and science communication targeted at promoting children's scientific literacy.

Insecticidal and repellent activity of typical monoterpenes from plant essential oils against Callosobruchus maculatus (Fabr. 1775)

Abstract: Synthetic insecticides and repellents have been broadly used worldwide for the control of crop pests and insects acting as vectors of human disease. Despite effectiveness, synthetic insecticides or repellents may cause serious damages to the environment and consequently to humans and animals. The growing biotechnological investigation for alternative insecticides and repellents, particularly of natural ones from plants, may conduce to higher safety and efficiency to the control of insects. Callosobruchus maculatus (Fabr. 1775) (Chrysomelidae) is a bruchid beetle that has been considered an important crop pest and also useful as model organism for development of new insecticides/repellents due several advantages such as a quick reproduction, sexual dimorphism and easy conditions of maintenance. As a crop pest, this insect, whose control by synthetic pesticides has been not straightforward, may represent an important threaten for bean (Vigna unguiculata L.) production in Brazil as well as other stored-grains cultivars in agriculture. Considering the need of new alternatives for C. maculatus control and the importance of monoterpenes in plant resistance against insects, the aim of this work was to evaluate the insecticidal and repellent activity of typical monoterpenes (geraniol, citral, ( ± ) citronellal, citronellol and eugenol) commonly found in plant essential oil against C. maculatus. To date, all of tested compounds presented a significant insecticidal and also repellent activity against C. maculates in a range of doses from 1 to 64 µL. The best tested compound as insecticide was the eugenol, while the best performance as repellent was accessed using eugenol. Thus, these data showed that evaluated monoterpenes presented significant insecticidal and repellent effects, which are of high biotechnological interest and useful towards the growth of agriculture worldwide.

Balanceamento de linha e arranjo físico: estudo de caso em uma linha de produção de cabines para máquinas de construção

Abstract: The adequate sizing of production capacity is fundamental to support the strategic positioning of a company in a globalized market, which is increasingly competitive. The aim of this study was to combine line balancing with facility layout optimization as a capacity adequacy strategy. To achieve this, a case study was carried out on a production line of cabins for construction machines at a Japanese multinational. As a result, the proposed line balancing, compared to the one used by the company, proved to be more efficient, optimizing the available resources. There were evident advantages in the joint analysis of line balancing with layout strategy.

Influence of upward and horizontal growth direction on microstructure and microhardness of an unsteady-state directionally solidified Al-Cu-Si alloy

Abstract: In order to analyze the effect of the growth direction on dendrite arm spacing (λ1) and microhardness (HV) during horizontal directional solidification (HDS), experiments were carried out with the Al-3wt.%Cu-5.5wt.%Si alloy and the results compared with others from the literature elaborated for upward directional solidification (UDS). For this purpose, a water-cooled directional solidification experimental device was developed, and the alloy investigated was solidified under unsteady-state heat flow conditions. Thermal parameters such as growth rate (VL) and cooling rate (TR) were determined experimentally and correlations among VL, TR, λ1 and HV has been performed. It is observed that experimental power laws characterize λ1 with a function of VL and TRgiven by: λ1=constant(VL)-1.1 and λ1=constant(TR)-0.55. The horizontal solidification direction has not affected the power growth law of λ1 found for the upward solidification. However, higher values of λ1 have been observed when the solidification is developed in the horizontal direction. The interrelation of HV as function of VL, TR and λ1 has been represented by power and Hall-Petch laws. A comparison with the Al-3wt.%Cu alloy from literature was also performed and the results show the Si element affecting significativaly the HV values.